Exploradio Origins: How to See Gravity Waves

In 1916, Einstein made a bold prediction- that gravity actually travels in waves. These “gravitational waves” would be ripples in the fabric of space a bit like ripples on a pond, and would slightly stretch and squash the distances between things as they passed.

“Einstein himself who came up with the theory didn’t think that this would ever really be detected,” Kenyon College professor Leslie Wade said.

Anything with mass can make gravitational waves by moving around, but they’re so small, the only waves we could possibly see are from the most energetic events in the universe, like two black holes smashing into each other. To look for these, scientists like Leslie and Madeline Wade, assistant professors of physics at Kenyon College joined thousands of others to build LIGO, the Laser Interferometer Gravitational Wave Observatory.

“We’re essentially measuring how much the two perpendicular arms of the interferometer have moved relative to each other by measuring how much light sent down these arms is constructively or destructively interfering," Madeline Wade said. "If I got this much light at my detector that meant each arm had to move by a certain amount.”

It took four decades to build and tune LIGO’s 4-kilometer-long interferometers, but finally, 100 years after Einstein’s prediction, they made their first gravitational wave detection in 2015. "It's certainly nice giving talks where we don't have to say 'when we find gravitational waves' and then people rolling their eyes," Leslie Wade said.

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